Centrifugal fan



Nov. l5, `1.932. H. F. HAGEN CENTRIFUGAL FAN Filed Feb. '3. 1930 I /NENTOR 7J MWM Malay A from/E Patented Nov. 15, 1932 UNITED STATES PATENTOFFICE HAROLD F. HAGEN, OF DEDHAM, MASSACHUSETTS, ASSIGNOR TO IB. F.'STURTEVANT COMPANY, lOF HYDE PARK, MASSACHUSETTS, A CQBPORATION OFMASSACHUSETTS CENTRIFUGAL FAN Application tiled February 3, 1930. SerialNo. 425,433.

The present invention relates to centrifugal fans. Y

The object of the present invention is to provide a simple and easilyoperatedcentrifugal fan, theoutput of which may be etlicientlycontrolled independently of the speed.

In my copending application, Serial No. 210,666, filed August 4, 1927, Ihave disclosed a method and apparatus whereby the output of acentrifugal fan may be controlled without the necessity of employing thecommon but expensive method of speed control or the ineiiicient methodof throttling. Briefly, the principle ofthe invention of saidapplication consists in output regulation by imparting to fthe enteringfluid a variable and controllable spin velocity in the direction ofrotation of prior invention includes a plurality of si-Y multaneouslyadjustable vanes to direct the entering fluid into the rotor `at avariable angle. A

The present invention, while operating on the principle of varyingoutput control of spin velocity, conslsts .of a modl cation of the priorinvention, principally with a vlew toward economy and simplicity ofconstruction. A

In its simplest form, it comprises an inlet chamber which by its shapehas an inherent tendency to introduce a spin into the Huid, togetherwith deilecting means adjacent the entrance opening of the chamber,thereby to control the direction of the entering currents of fluid andthus to vary the spin component of velocity. Such deflecting means doesnot constitute a throttling means because although the air passage maybe reduced in cross-sectional area, the volume of fluid passing isitself so far reduced by the limitation of the output of the fan, due toincreased spin of the air, that the objectionable features of throttlingare entirely avoided.

In the accompanyin drawing illustratin 'what is now considere the(preferred form o the invention, Fig. 1 is a si e elevation of aninduced draft fanwith the output controlling means in position formaximum output; Fig. 2 is an end elevation of the fan shown in Fig. 1;`-and Fig. 3 is a view similar to Fig. l showing the output controllingmeans in position for reduced output.

The illustrated embodiment of the invention comprises a fan having arotor 4, inlet boxes 6 and 8v on opposite sides of the rotor and anoutlet box or scroll 10. The inlet boxes 6 and 8 being of identicalconstruction, a description of one only will sufiice. The

`fan, is curved away from the eye for a, short distance, The wall 18 isof circular contour havlng its center directly below the axis of Atherotor and curving 1n the same general direction as wall 16, but moresharply. The walls 16 and 18 meet the scroll portion ofthe inlet box ina constricted throat 20.

In order to control and vary the ma itude of the spin velocity ofthefluid a mitted to the rotor, the entrance chamber 14 is provided with apivoted gate or def-lector 22 which is in the sha e of a sector having acurved plate 24 coniibrming to the inside of the wall'18 and alsoprovided with a reversed lip 26 which conforms to the throat portionofthe inlet box when the gate is completely open as shown in Fig. 1. Thedeflector. is also formed with side plates 28 which are secured to arock shaft 29. The defiector is counter-balanced by a weight 30 and isadapted to be moved to any desired position by a link 32 attached to therock shaft. By

means of the lever 32, the deflector may be moved from full openposition, as shown in Fig. 1, through an intermediate position, as shownvin Fi 3, to fully closed position wherein lthe 11p 26 engages with thewall 16V of the entrance chamber.

upper part of the inlet box 6 is of the usual i scroll formation, asindicated at 11. The

By variation of the positionof the deiector 18, the magnitude of thespin velocity of the fluid entering the rotormay be convenientlyadjusted. When the deiector is in the posi- -tion shown in Fig. 1, theair enters the inlet side wall of the scroll before entering the eye.The amount of rotation which the fluid thus assumes in this position ofthe deflector is, however, too smallto cause any serious reduction infan capacity. In fact, this slight rotation is advantageous in that itcauses the fluid to distribute itself uniforml around the eye of thefan. At the open pos`1- tion of the deilector, therefore, the fluid enters the eye along nearly radial lines, and with minimum spin, so thatmaximum output is obtained.

When the deflector is adjusted, say to the position of Fig. 3, theentering fluid follows the eneral direction of the arrows and beinginitially confined to the space immediately adjacent to the outside wallof the scroll, tends to circulate more completely around the casing andto assume a much greater angle of entrance into the eye of the fan. Infact, the iuid may spin more than one complete revolution around thecasing before passing into the fan. In other words, the fluid, insteadof passing into the eye of the fan along nearl radial lines, now assumesa directionwhic deviates from the radial and approaches the tangential.The spin velocity in the d irectionv of rotation is thereby increasedand the fan is able to do only a decreased amount of work on the fluid.As the deilector is moved farther toward the left in Fig. 3, thecomponent of spin velocity increases and the work done by the fan uponthe air is further decreased. Thus, the fan may operate at constantspeed, as with an induction motor drive, without the necessity foremploying complicated speed control or ineiiicient throttling devices.It will be noted, that. although the deflector 18, as it is moved fromthe position of Fig. 1 to that of Fig. 3, progressively reduces the areaor opening of the throat 20, nevertheless no appreciable throttlingoccurs. The construction is such that as the deflector is moved to theleft of Fig. 3, .the spin velocity is so greatly increased that itbecomes the predominant factor in determining the Work done by the fanand reduces the volume of air to such an extent that it may freely flowthrough the reduced area ofthe throat without producing any throttlingeifect or appreciable lloss in efficiency. A

The fan described above may be employed for either forced draft orinduced draft` or in fact, for any purpose for which centrifugal fansare adapted. For forced draft, the entrance chamber 14 may open directlyto the admission of fluid to the eye, whereby the output of the fan maybe controlled.

2. A fan comprising an inlet box including a scroll having an eccentriceye and an -entrance chamber connected with the scroll and having anadjustable curved fluid directing wall to direct the luid to a greateror lessf extent into the outer peripheral portion of4 the scroll, andmeans for adjusting said wall to vary the spin velocity of fluidadmitted to the rotor.

3. A fan comprising a rotor, an inlet scroll having an eye, an entrancechamber connected with the inlet scroll, the scroll being shaped tocause the fluid to assume a spin velocity prior to the entrance into theeye, and means for varying the spin velocity attained in the scrollincluding a deflector to vary the direction of delivery of the fluid tothe scroll .from the entrance chamber.

1. A fan comprising an inlet scroll, an entrance chamber therefor havinga curved fluid directing wall merging with the scroll,

the scroll having an eccentric eye at a dis' tance from the fluiddirecting wall and nearer the opposite wall of the scroll, a rotor, anda deflector in the entrance chamber adapted to be moved toward the fluiddirecting wall to direct the fluid entering the scroll to a greater orless extent into the outer periphe of the scroll to increase the spinvelocity an thereby'to decrease the output of the fan.

5. A fan comprising an unobstructed inlet scroll having an eyeeccentrically positioned therein, an entrance chamber through which thefluid passes prior to entrance into the scroll, and means exteriorly ofthe scroll for varying the direction of delivery of air from the chamberto the scroll to control the output of the fan.

6. A fan comprising an inlet scroll, an entrance chamber having a.curved wall for directing the delivery of air to the scroll, and acurved deflector adjacent said wall and adjustable to form a variableextension thereof to control the direction of the air entering thescroll from the chamber.

7. A fan comprising an inlet chamber having an eye therein, an entrancechamber opening into the inlet chamber, the inletchamber having a curvedwall to rotatevthe fluid in its passage toward the eye, and movableymeans for varying the opening of the entrance chamber into .the inletchamber to regifilate the spin ofthe air and output of the 8. A fancomprising an inlet chamber having an eye therein, the inlet chamberhaving a curved Wall to rotate the fluid in its assage toward thee e, anentrance chamber aving an opening into the inlet`chamber for deliveringair from the former to the latter and eccentrically of the eye, andmeans bem tween the entrance and the inlet chamber for determining theextent of eccentricity of such delivery.

9. A ian comprisi a rotor, an inlet scroll having an eccentric eyeleadin to the u. rotor and an entrance opening where om the fluidcirculates about the scroll to attain a spin component of velocity riorto passing through the eye, and adjusta le means at the having.- anentrancev opening to admit the iuidinto the chambertangentially of theeye to cause the fluid to circulate about thel c tained by the fluid incirculating about the` chamber to the eye.

In testimony'whereof I have signed my name to this specification. v

` HAROLD F. HAGEN.

entrance openingi for vail'ying the spin n velocity attained in the scr10. A fan cromprising a rotor, an inlet Y scroll having an eccentric eyeleading to -the rotor and an entrance opening wherefrom the fluidcirculates about the scroll to attain Si a spin component of velocityprior to passing through the eye, and adjustable means at the entranceopening for variabl directing the fluid toward the outer wall o thescroll.

11. A fan comprising 'an inlet scroll having an eccentric eye, a rotor,an entrance 'chamber connected with thescroll and having curved walls todirect iiuid toward the outer peripheryof` the scroll, and an adjustabledeilector to vary the extent of fluid direction to'ward the outerperiphery of the scroll to vary the s in velocity assumed by the fluidin passing about the scroll.

12. A fan comprising a. rotor, -an inlet chamber having a. curved outerwall and an eye-leadingto the rotor, the chamber hav-- 40 ing anentrance opening to admit the luidv into the chamber tangentiall of theeye to cause the fluid to circulate a ut the chamber and thereby toattaina spin com nent of velocity prior to passing through t e eye, andadjustable means for directing theiluid to a greater or less extent intothe outer peripheral portion of the inlet chamber to adjust the s inveloci of the fluid.

13. A' an comprising a rotor, an inlet chamber having a curved outerwall and an eye leading to the `rotor, the chamber having an entranceopening to admit the fluid into the chamber tangentiall of the e e tocause the fluid to circulate a ut the c amber and thereby to attain' aspin component of velocity prior to passin through the eye,

and a deflector for initi y directing the fluid to a ater or less extentinto'the outer peripherallle vary thgspin' velocity attained by thefluid in circulating about the chamber.

14. A fan comprising a rotor, an inlet chamber having a curved outerwall and g5 an eye leading to the rotor, theA chamber portion oftheinlet chamber to .isc

